<div class="time-duration row">
  <div class="col-xs-12">
    <h1>自定义指令</h1>
    <div class="col-xs-6">
      <input ng-model='num' class="form-control">
    </div>
    <div class="col-xs-6">
      <select ng-model='unit' class="form-control">
          <option value="seconds">Seconds</option>
          <option value="minutes">Minutes</option>
          <option value="hours">Hours</option>
          <option value="days">Days</option>
      </select>
    </div>
  </div>
</div>
